Physical vapor deposition (PVD) is commonly utilized for formation of thin layers. For instance, PVD is commonly utilized for deposition of the thin layers utilized in semiconductor structures, with PVD being particularly useful for deposition of metallic materials. PVD processes are commonly referred to as sputtering processes, in that the processes comprise sputtering of desired materials from a target. The sputtered materials are deposited across a substrate to form a desired thin film.
An exemplary PVD operation is described with reference to an apparatus 110 in FIG. 1. Apparatus 110 is an example of an ion metal plasma (IMP) apparatus, and comprises a chamber 112 having sidewalls 114. Chamber 112 is typically a high vacuum chamber. A target 10 is provided in an upper region of the chamber, and a substrate 118 is provided in a lower region of the chamber. Substrate 118 is retained on a holder 120, which typically comprises an electrostatic chuck. Target 10 would be retained with suitable supporting members (not shown), which can include a power source. An upper shield (not shown) can be provided to shield edges of the target 10. Target 10 can comprise, for example, one or more of aluminum, cadmium, cobalt, copper, gold, indium, molybdenum, nickel, niobium, palladium, platinum, rhenium, ruthenium, silver, tin, tantalum, titanium, tungsten, vanadium and zinc. The elements can be in elemental, compound, or alloy form. The target can be a monolithic target, or can be part of a target/backing plate assembly.
Substrate 118 can comprise, for example, a semiconductor wafer, such as, for example, a single crystal silicon wafer.
Material is sputtered from a surface of target 10 and directed toward substrate 118. The sputtered material is represented by arrows 122.
Generally, the sputtered material will leave the target surface in a number of different directions. This can be problematic, and it is preferred that the sputtered material be directed relatively orthogonally to an upper surface of substrate 118. Accordingly, a focusing coil 126 is provided within chamber 112. The focusing coil can improve the orientation of sputtered materials 122, and is shown directing the sputtering materials relatively orthogonally to the upper surface of substrate 118.
Coil 126 is retained within chamber 112 by pins 128 which are shown extending through sidewalls of the coil and also through sidewalls 114 and chamber 112. Pins 128 are retained with retaining screws 130 in the shown configuration. The schematic illustration of FIG. 1 shows heads 132 of the pins along an interior surface of coil 126, and another set of heads 130 of the retaining screws along the exterior surface of chamber sidewalls 114.
Spacers 140 (which are frequently referred to as cups) extend around pins 128, and are utilized to space coil 126 from sidewalls 114.
The coil 126 is generally provided within the chamber 112 as a kit comprising the pins 128, retaining screws 130, cups 140, and various other components which are not shown in FIG. 1. The coils utilized in such kits will comprise annular rings (referred to herein as annular coil bodies) having openings extending therethrough. FIGS. 2 and 3 illustrate exemplary prior art coil constructions 200 and 250, respectively. Either of the coil constructions 200 or 250 can be utilized for the coil 126 of FIG. 1. Both of the coil constructions are annular rings which are substantially circular (with the term “substantially circular” indicating that the rings are circular to within tolerances of an application process, which includes, but is not limited to, applications in which the rings are circular in a strict mathematical sense).
Coil 200 has an inner periphery 202 and an outer periphery 204; and similarly coil 250 has an inner periphery 252 and an outer periphery 254.
Coil 200 has a plurality of openings 206, 208 and 210 extending therethrough for receipt of pins (such as the pins 128 of FIG. 1) utilized to retain the coil within a PVD chamber. Similarly, coil 250 comprises a plurality of openings 256, 258 and 260 extending therethrough for receipt of pins.
Coil 200 comprises a pair of openings 212 and 214 configured for receipt of a pair of electrode assemblies which provide power to the coil. Openings 212 and 214 are separated from one another by a slot 216. The shape of the slot corresponds to a so-called step-in-and-step-out configuration. The coil 250 of FIG. 3 comprises a pair of openings 262 and 264 configured for receipt of electrodes, and separated from one another by a slot 266. The configuration of the slot 266 of coil 250 corresponds to a “side-by-side” configuration.
FIG. 4 shows a coil to shield attachment of the type described in FIG. 1, but in greater detail than shown in FIG. 1, and with more accuracy to detail. Referring to FIG. 4, identical numbering will be used as was utilized in describing FIG. 1, where appropriate, but it is to be understood that the coil can comprise either coil 200 or coil 250 of FIGS. 2 and 3. FIG. 4 shows coil 126 attached to shield 114 (i.e., to chamber sidewall 114). The attachment utilizes a pin 128 having a threaded interior 129, and a screw 130 retained within such threaded interior. Pin 128 comprises a head 132 which is inset within the inner periphery of coil 126. Screw 130 comprises a head 131 which projects outwardly of shield 114 in the shown configuration.
Pin 128 extends through the electrically conductive cup 140. Pin 128 also extends through an inner conductor 141 which is within cup 140. The cup and inner conductor together form a construction having a projecting lip 143 extending around a recess 145. The pin extends through an opening 147 in the cup and inner conductor.
A dielectric material spacer 151 is provided around the assembly comprising cup 140 and inner conductor 141, and is utilized to space the conductive materials of cup 140 and inner conductor 141 from shield 114. Spacer 151 can comprise any suitable material, and typically comprises one or more ceramic materials. A similar dielectric 153 is within shield 114 to isolate the screw 130 from the shield.
Coil 126 will wear out with time, and kits are provided for replacement of the coil. Such kits will typically comprise a coil having a configuration similar to that shown in either FIG. 2 or 3, together with numerous separate components for attaching the coil to a shield, with such separate components including, for example, pins (such as the pin 128), cups (such as the cup 140), and inner conductors (such as the inner conductor 141). The kit is assembled in order to provide the coil within the chamber. FIG. 5 is a view along an outer periphery of a partially assembled kit. Such view shows the coil 126, cup 140, inner conductor 141 and pin 128. The view of FIG. 5 shows that the lip 143 extends entirely around the recess 145.
The kit utilized for retaining a new coil within a sputtering chamber will typically also comprise assemblies for the electrodes which are to be utilized with the coil. FIG. 6 illustrates a diagrammatic view of an electrode assembly. FIG. 6 shows the coil 126 having an opening 161 extending therethrough, and having a pin 163 within the opening. Opening 161 can correspond to, for example, any of the openings 212, 214, 262 and 264 discussed previously with reference to FIGS. 2 and 3. Pin 163 has a threaded interior periphery 165. A clamp 167 is provided over the pin, and a screw 169 is threadably engaged with the interior periphery 165 of the pin. An appropriate power source would be connected with the electrode and utilized for providing power to coil 126, as is known to persons of ordinary skill in the art.
The coil structures of FIGS. 1-6 are exemplary prior art coil structures. Other coil structures have been constructed. For instance, monolithic coil structures have been constructed in which the electrode assemblies are one-piece with a coil, and in which cups and inner conductors are one-piece with the coil. An advantage of forming the electrodes, cups and inner conductors as one-piece with a coil is that such can eliminate utilization of pins (such as, for example, the pin 128 of FIG. 4 and the pin 163 of FIG. 6), which can eliminate discontinuities along an inner peripheral surface of a coil by eliminating the recessed pinhead otherwise present along the inner periphery of the coil. An advantage of eliminating the discontinuities from the inner periphery of the coil is that such can improve longevity of the coil, and performance of the coil.
The monolithic coil structures produced have been for utilization in modified physical vapor deposition apparatuses. In other words, the monolithic coil assemblies have not corresponded to assemblies which can be substituted for the kit constructions utilized in conventional physical vapor deposition apparatuses, but instead have differences which make them suitable for apparatuses other than the conventional apparatuses described above. For instance, one of the monolithic coil assemblies lacks the lip 143 of FIGS. 4 and 5 which extends entirely around the recess 145, and instead utilizes a lip which extends only partially around such recess.
It would be desirable to develop new configurations for coil constructions.